[论文解读] Coupled thermo-chemo-mechanical phase field-based modelling of hydrogen-assisted cracking in girth welds

L. Castro, Y. Navidtehrani. C. Betegón+1 more|arXiv (Cornell University)|Jan 1, 2026

Hydrogen embrittlement and corrosion behaviors in metals被引用 0

一句话总结

论文提出了一种将热-机械焊接仿真与多陷阱氢扩散和氢敏感相场断裂模型耦合的计算框架，用以在氢暴露下预测 X80 管线对焊接完整性。

ABSTRACT

A new computational framework is presented to predict the structural integrity of welds in hydrogen transmission pipelines. The framework combines: (i) a thermo-mechanical weld process model, and (ii) a coupled deformation-diffusion-fracture phase field-based model that accounts for plasticity and hydrogen trapping, considering multiple trap types, with stationary and evolving trap densities. This enables capturing, for the first time, the interplay between residual stresses, trap creation, hydrogen transport, and fracture. The computational framework is particularised and applied to the study of weld integrity in X80 pipeline steel. The focus is on girth welds, as they are more complex due to their multi-pass nature. The weld process model enables identifying the dimensions and characteristics of the three weld regions: base metal, heat-affected zone, and weld metal, and these are treated distinctively. This is followed by virtual fracture experiments, which reveal a very good agreement with laboratory studies. Then, weld pipeline integrity is assessed, estimating critical failure pressures for a wide range of scenarios. Of particular interest is to assess the structural integrity implications of welding defects present in existing natural gas pipelines under consideration for hydrogen transport: pores, lack of penetration, imperfections, lack of fusion, root contraction, and undercutting. The results obtained in hydrogen-containing environments reveal an important role of the weld microstructure and the detrimental effect of weld defects that are likely to be present in existing natural gas pipelines, as they are considered safe in gas pipeline standards.

研究动机与目标

• 从多道对焊接的 X80 钢获得残余应力与热影响区 (HAZ) 性能表征。
• 开发包含塑性、氢陷阱与相场断裂的耦合变形-扩散-断裂模型。
• 在氢环境下评估焊缝完整性并识别常见焊缝缺陷的影响。
• 评估焊缝显微结构与缺陷如何影响氢辅助断裂在对焊中的表现。

提出的方法

• 将焊接过程建模为一个随温度变化材料属性的序贯热-机械问题。
• 使用 Abaqus 与 UMAT 在多道 SMAW 焊接中模拟弹塑性热-机械响应。
• 定义三种焊缝区域（BM、WM、HAZ）并赋予不同属性，将焊接结果耦合到后续断裂分析。
• 实现一个两级（晶格-陷阱）氢传输模型，包含多种陷阱类型，且陷阱创建由塑性变形驱动。
• 应用对氢敏感的弹塑性相场断裂模型，其中裂纹扩展由历史场驱动，材料韧性随晶格氢含量而变化。
• 采用与材料强度相关的长度尺度参数的 AT2 相场公式来捕捉裂纹的起始与扩展。

实验结果

研究问题

• RQ1 多道对焊接产生的残余应力如何在服务温度下影响不同焊缝区域（BM、WM、HAZ）的氢扩散与陷阱？
• RQ2 耦合的热-机械焊接仿真结合多陷阱氢扩散与相场断裂能否准确预测 X80 对焊在氢暴露下的氢辅助断裂？
• RQ3 典型焊缝缺陷（孔洞、未熔合、欠蚀、根部收缩等）对氢脆和焊接管线断裂风险有何影响？
• RQ4 塑性变形过程中滑移位错陷阱密度的演化如何影响氢传输与断裂抗力？
• RQ5 模型在 BM、WM 和 HAZ 在氢富环境中的实验断裂行为再现程度如何？

主要发现

• 热-机械焊接仿真能区分 BM、HAZ、WM 区域，并在焊根附近揭示高达约 730 MPa 的残余拉应力。
• HAZ 的宽度约为 3 mm，与实验观测一致，残余应力场呈现厚度相关的变化。
• 耦合的变形-扩散-断裂框架能捕捉氢陷阱与扩散效应，使在氢暴露下的裂纹起始与扩展具备预测能力。
• 天然气管道中常见的焊缝缺陷（孔洞、未焊透、未熔合、根部收缩、欠蚀）在氢环境中对结构完整性具有显著不利影响。
• 该模型在 BM、WM、HAZ 的实验室断裂实验中显示良好的一致性，并可用于估计带缺陷管线的临界失效压力。